Information processing devices such as portable telephones or personal digital assistants (PDA) as well as laptop computers and the like always provide illumination for a liquid crystal display that displays images and characters, and now it is common for these types of devices to provide illumination of the parts of the device for operating the keys as well.
For example, as disclosed in the following Patent Document 1, in the portable telephone device both the display part and the key operating part are each provided with a dedicated light source. The liquid crystal display part is lighted by a backlight utilizing a light guide plate, while the key operating part is illuminated by an LED or the like attached to a substrate.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2004-295187
[Patent Document 2] Patent publication No. 2004-508599